I want to do TGA analysis of one compound, sodium tungstate di- hydrate. But, I can't fully understand the results of TGA of said compound.
Actually, the %age of Tungsten is not in line with the precursors %age after analysis by EDS. According to my observations, most of the Tungsten metal evaporates in the calcination process.
I want to know the exact calcination temperature profiles (TGA profiles) of tungsten related compounds.
Reference of any research paper will be highly appreciated.
Thanks in advance
May be tungstain-sodium oxide simply losing and removed with flow of water vapour? Make minimal load and repeat measurement. Also, do not use high velocity of heating.
@ Anna Matveyeva
I have used sodium tungstate (Na2WO4.2H2O) instead of ammonium tungstate that you are talking about.
For the case of sodium tungstate, I set the temperature of 500 oC in furnace for calcination phenomenon. At this temperature, tungsten oxide (VI) couldn't exist.
At 700 oC, how is it possible..?
2nd thing, your attached pdf file is about ammonium tungstate or ammonium molybdate..?
please send me the clear relevant data regarding ammonium para tungstate or sodium tungstate if you have..
thanks
@ Omar M S
Thank you Sir...
if you send me the book or relevant chapter of that book then it will be best for me.
Regards,
Tariq
@ Vadim S. Gorshkov ..
Thank you for suggestion...
I have replicated the experiments and reduce the load but in vein. if you have any other suggestion then let me know..
Regards,
tariq
A control and a benchmark experiment is always useful before using analytical instrument to ensure that the instrument is working perfectly. It may churn out a number/graph, but what is the reliability of those numbers? You can test a standard compound with TGA before testing anything in the desired temperature range.
As a rule of thumb, whenever you report TGA there are five things which are critical: one is the sample morphology, crucible material, rate of heating, atmosphere of the TGA, and mass of the sample. The acronym is called SCRAM. The appearance of TGA curve will differ on the basis these variables, therefore literature TGA will not match with yours until and unless all these 5 things are comparable.
One should not use EDS to compare TGA data either. EDS is merely a surface analysis technique, whereas TGA analyzes the bulk.
This paper may be helpful:
Article Thermal and Electrical Properties of Tungsten Oxide (WO3)
1. Do not exist TGA at all: there exist specific experiment with exact conditions: equipment, load, max temperature, heat velocity, gas flow etc.
2. For TG analysis, mostly the results of the experiment are sufficient, literature data are not needed (only for case, if the fantastic results are obtained ).
3. Miracles do not happen.
Therefore, we can discuss your experiment, if you explain us conditions, as well as show resulting TG/DTA (DSC) curve.
Regards.
Muhammad Tariq
Oh, sorry, I actually added the wrong file.
Now it is correct file - an ammonium metatungsate. Here the temperature of 700 degrees was enough for the decomposition. Further, according to the literature, there is a sublimation of the oxide.
BW
Anna
Of some possible interest for your query ― in case sodium tungstate is previously acidified with hydrochloric acid ― it can be then expected to yield WO3·H2O (85―185 ºC), before dehydrate to WO3 (with NaCl); cf.: http://repository.kulib.kyoto-u.ac.jp/dspace/handle/2433/74272
- Badges
- Science topic
- Similar topics
- Methodology
- Research Methodology
- Research Papers